Systems and methods for additive manufacturing using aluminum metal-cored wire

ABSTRACT

A method of forming an additively manufactured aluminum part includes establishing an arc between a metal-cored aluminum wire and the additively manufactured aluminum part, wherein the metal-cored aluminum wire includes a metallic sheath and a granular core disposed within the metallic sheath. The method includes melting a portion of the metal-cored aluminum wire using the heat of the arc to form molten droplets. The method includes transferring the molten droplets to the additively manufactured aluminum part under an inert gas flow, and solidifying the molten droplets under the inert gas flow to form deposits of the additively manufactured aluminum part.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of U.S.Provisional Application Ser. No. 62/120,752, entitled “ALUMINUMMETAL-CORED WELDING WIRE,” filed Feb. 25, 2015, which is herebyincorporated by reference in its entirety for all purposes.

BACKGROUND

The present disclosure relates to systems and methods for additivemanufacturing using a tubular aluminum wire as a source material.

Additive manufacturing systems generally involve the construction ofparts in a bottom-up fashion. In generally, in additive manufacturing,the parts may be formed in a deposit-by-deposit or layer-by-layerprocess, whereby a source material is successively deposited on top ofitself to gradually form (e.g., build or print) a completed part.Additive manufacturing systems are useful for rapid prototyping, and canproduce complex parts with a high degree of precision and with littlewaste of source material. Different additive manufacturing systems canuse different types of source materials, such as metals, polymers, andceramics, to construct different types of parts.

Aluminum and aluminum alloys are widely used as construction materialdue to their relatively low density and high corrosion resistancecompared to other metals. For example, aluminum alloys may providestrengths between approximately 50 megapascal (MPa) and approximately700 megapascal (MPa). Since aluminum has a high affinity for oxygen,aluminum part fabrication may involve the use of an inert shielding gasto limit or prevent the formation of aluminum oxide (alumina) andundesirable inclusions. It may also be desirable to fabricate aluminumparts with relatively low porosity. One prominent source of such poresmay be hydrogen that is released from, and forms voids within, thesolidifying metal during part fabrication. Hydrogen gas may be formedvia the decomposition of hydrogen-containing materials (e.g., moistureor organic materials, such as lubricants) during aluminum partfabrication. As such, it is desirable to prevent hydrogen-containingmaterials from being introduced into the additive manufacturingenvironment.

BRIEF DESCRIPTION

In an embodiment, a method of forming an additively manufacturedaluminum part includes establishing an arc between a metal-coredaluminum wire and the additively manufactured aluminum part, wherein themetal-cored aluminum wire includes a metallic sheath and a granular coredisposed within the metallic sheath. The method includes melting aportion of the metal-cored aluminum wire using the heat of the arc toform molten droplets. The method includes transferring the moltendroplets to the additively manufactured aluminum part under an inert gasflow, and solidifying the molten droplets under the inert gas flow toform deposits of the additively manufactured aluminum part.

In an embodiment, an additive manufacturing system includes a torchconfigured to receive shielding gas and metal-cored aluminum wire. Themetal-cored aluminum wire includes a metallic sheath and a granular coredisposed within the metallic sheath. The torch is configured toestablish an arc between the metal-cored aluminum wire and an additivelymanufactured part. The torch is configured to form a molten portion ofthe metal-cored aluminum wire using the heat of the arc under anatmosphere of the shielding gas, and to transfer the molten portion tothe additively manufactured part to form a deposit of the additivelymanufactured part under the atmosphere of the shielding gas.

In an embodiment, an additively manufactured aluminum alloy partincludes a plurality of aluminum alloy deposits fused together to form aplurality of layers of the additively manufactured aluminum alloy part,wherein the additively manufactured aluminum alloy part is additivelymanufactured using a metal-cored aluminum wire that comprises a metallicsheath and a granular core disposed within the metallic sheath.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic of an embodiment of an additive manufacturingsystem that utilizes metal-cored aluminum wire as a source material, inaccordance with the present disclosure;

FIG. 2A is a cross-sectional schematic of a seamless metal-coredaluminum wire, in accordance with embodiments of the present technique;and

FIG. 2B is a cross-sectional schematic of a metal-cored aluminum wirethat includes a seam, in accordance with embodiments of the presenttechnique.

FIG. 3 is an example block diagram of the steps of an additivemanufacturing method, in accordance with embodiments of the presenttechnique.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Furthermore, as used herein, “approximately” may generally refer to anapproximate value that may, in certain embodiments, represent adifference (e.g., higher or lower) of less than 0.01%, less than 0.1%,or less than 1% from the actual value. That is, an “approximate” valuemay, in certain embodiments, be accurate to within (e.g., plus or minus)0.01%, within 0.1%, or within 1% of the stated value. Likewise, twovalues described as being “substantially the same” or “substantiallysimilar” are approximately the same, and a material that is described asbeing “substantially free” of a substance includes approximately 0% ofthe substance. The terms “metal-core” and “metal-cored” are used hereinto refer to tubular wires having a metallic sheath and a granular core,wherein the core primarily includes metallic alloying powders with lowamounts (i.e., less than about 5 wt %) of non-metallic components (e.g.,slag forming agents, metal oxides, stabilizers, etc.). For example, seeANSI/ANS A5.9 Specifications for Bare Stainless Steel Welding Electrodesand Rods. As used herein, the term “non-metallic component” refers toelements and compounds of elements that are not metals or metalloids(e.g., hydrogen, carbon, nitrogen, oxygen, phosphorous, sulfur,halides).

As used herein, “melting point” refers to the temperature or temperaturerange at which a solid substance is converted to a liquid. When thesolid substance is a mixture, as in the case of alloys and mixtures ofpowders, the melting point usually encompasses a range of temperaturesbetween a solidus and a liquidus, in which “solidus” refers to thetemperature at which the mixture begins to melt, and “liquidus” refersto the temperature at which the mixture is completely liquefied. Incontrast, pure solid substances tend to have a sharp, narrow meltingpoint (i.e., the solidus and liquidus are substantially the same). Oneexceptional mixture, discussed in greater detail below, is a eutecticalloy. As used herein, a “eutectic alloy” refers to an alloy in whichthe solidus and liquidus are substantially the same, resulting in asharp melting point at its eutectic temperature, which is lower than themelting points of the individual elements of the alloy. As such, it maybe appreciated that the terms “solidus” and “melting point” are hereinused interchangeably when referring to substances with sharp meltingpoints, such as pure substances and eutectic alloys. As used herein, a“near-eutectic alloy” refers to an alloy that is made from the sameelemental components as a eutectic alloy, albeit using slightlydifferent relative amounts of these elements, to yield a slightlyhypoeutectic or hypereutectic composition, wherein the liquidus andsolidus differ from one another by less than approximately 20% (e.g.,less than approximately 10%, less than approximately 5%).

Present embodiments are directed toward systems and methods for additivemanufacturing parts made of a diverse range of different aluminum alloysusing tubular aluminum wires (i.e., metal-cored aluminum wires) as thesource material. The disclosed metal-cored aluminum wires include aseamed or seamless aluminum or aluminum alloy sheath encircling agranular core, which is a compressed mixture of powdered metals, alloys,and/or non-metallic components. More specifically, as discussed ingreater detail below, the disclosed metal-cored aluminum wireembodiments include a core that at least partially melts at a relativelylow temperature, which prevents a portion of the powdered core frombeing carried away by the shielding gas, thereby improving thedeposition rate of the wire during manufacturing. Accordingly, for themetal-cored aluminum wire embodiments discussed below, the core includesat least one alloy having a low melting point, relative to the meltingpoints of the individual elements of the alloy, relative to the meltingpoints of other components of the core, relative to the melting point ofthe sheath, or a combination thereof.

For example, for the metal-cored aluminum wire embodiments discussedbelow, one or more alloying elements are present within the core as analloy (e.g., eutectic alloy or near-eutectic alloy) having a meltingpoint (or solidus) that is substantially lower than the melting pointsof the individual elements of the alloy. In certain embodiments, thecore of the metal-cored aluminum wire may include at least one alloyhaving a melting point (or solidus) that is substantially lower than themelting points (or solidi) of other powdered metallic components of thecore. In certain embodiments, the composition of the core may be suchthat there is a substantial difference between the temperature at whichthe core begins to melt (i.e., the solidus of the core) and thetemperature at which the sheath begins to melt (i.e., the solidus of thesheath). As discussed below, the presently disclosed metal-coredaluminum wires enable the production of low-porosity and high-strengthaluminum parts at a high deposition rate. Moreover, as discussed ingreater detail below, the presently disclosed metal-cored aluminum wiredesigns enable the production of aluminum alloy parts having wide rangeof different aluminum chemistries. Further, the disclosed metal-coredaluminum wire enables significantly more flexibility on batchquantities, allowing for the on-demand production of limited numbers ofspecialized wires whose chemistries are precisely tuned to match thecompositions of particular part specifications. Further, in contrastwith solid aluminum wires, the composition of the disclosed metal-coredaluminum wire does not significantly impact the ability to manufacturethe wire.

Turning to FIG. 1, an embodiment of an additive manufacturing isillustrated that additively forms (e.g., prints, builds) an aluminumalloy part 12 using a metal-cored aluminum wire 14, in accordance withthe present disclosure. In general, the additive manufacturing system 10includes a torch 16 that deposits molten droplets 18 of a metal-coredaluminum wire 14 to form (e.g., print, build) the part 12 in adeposit-by-deposit and/or layer-by-layer fashion. A deposit 20, as usedherein, refers to a portion of the source material (i.e., themetal-cored aluminum wire 14) that has been transferred to, andsolidified to form a smallest unit of the additively manufactured part12. A layer 22, as used herein, refers to a collection of deposits 20having a similar dimension (e.g., thickness) that are depositedalongside one another to form a larger portion of the part 12.

The illustrated additive manufacturing system 10 has a number ofsubsystems, including a control system 24, a power system 26, a wirefeed system 28, a gas supply system 30, and a robotic system 32. Thecontrol system 24 includes a controller 34 that executes instructions togenerally control operation of the additive manufacturing system 10 tocause the part 12 to be manufactured. The power system 26 generallysupplies power to the additive manufacturing system 10, and isillustrated as being coupled to the wire feed system 28 via a connection38 and coupled to a portion of the part 12 via a connection 40 and aclamp 42 to provide a complete circuit between the power system 26, thetorch 16, and the part 12. In the illustrated embodiment, themetal-cored aluminum wire 14 is electrified within the wire feed system28 using power supplied by the power system 26, before the electrifiedwire 14 is provided to the torch 16 (e.g., directly or within aprotective conduit). In another embodiment, the power system 26 maycouple and directly supply power to the torch 16, and the metal-coredaluminum wire 14 may instead be electrified at the torch 16.

The power system 26 may generally include power conversion circuitrythat receives input power from an alternating current power source(e.g., an AC power grid, an engine/generator set, or a combinationthereof), conditions the input power, and provides DC or AC output powervia the connection 38. The power system 26 may power the wire feedsystem 28 that, in turn, provides a feed of electrified metal-coredaluminum wire 14, in accordance with demands of the additivemanufacturing system 10, to establish an arc 44 between the metal-coredaluminum wire 14 and the part 12. The power system 26 may includecircuit elements (e.g., transformers, rectifiers, switches, and soforth) capable of converting the AC input power to a direct currentelectrode positive (DCEP) output, direct current electrode negative(DCEN) output, DC variable polarity, pulsed DC, or a variable balance(e.g., balanced or unbalanced) AC output, as dictated by the demands ofthe additive manufacturing system 10 during manufacture of the part 12.

The illustrated additive manufacturing system 10 includes a gas supplysystem 30 that supplies a shielding gas or shielding gas mixtures to thetorch 16 during the additive manufacturing process. In the depictedembodiment, the gas supply system 30 is directly coupled to the torch 16via a gas conduit 46. In another embodiment, the gas supply system 30may instead be coupled to the wire feed system 28, and the wire feedsystem 28 may regulate the flow of gas from the gas supply system 30 tothe torch 16. Shielding gas, as used herein, may refer to any inert gasor mixture of inert gases that may be provided to the arc and/or themolten deposit (e.g., droplets 18) in order to provide a substantiallyinert local atmosphere (e.g., reduced in oxygen or substantially free ofoxygen) near the molten and solidifying portions of the part 12 duringadditive manufacturing. In certain embodiments, the shielding gas flowmay be a shielding gas or shielding gas mixture (e.g., argon (Ar),helium (He), nitrogen (N₂), similar suitable shielding gases, or anymixtures thereof). For example, a shielding gas flow (e.g., deliveredvia the gas conduit 46) may be 100% Ar or 100% He. In certainembodiments, the shielding gas flow may be an Ar/He mixture (e.g., 50%Ar/50% He; 25% Ar/75% He), which is presently recognized to enablebetter quality for the part 12 than pure Ar or pure He alone, when usedin combination with embodiments of the disclosed metal-cored aluminumwires 14.

Accordingly, the illustrated torch 16 generally receives the metal-coredaluminum wire 14 from the wire feed system 28, power from the powersystem 26, and a shielding gas flow from the gas supply system 30 inorder to perform additive manufacturing of the aluminum part 12. Duringoperation of the illustrated additive manufacturing system 10, the torch16 and the part 12 are brought in close proximity so that the arc 44 maybe struck and a portion of the wire 14 melted and transferred to thepart 12. As such, the additive manufacturing system 10 illustrated inFIG. 1 includes the robotic system 32, which includes sensors, motors,gears, tracks, or other suitable mechanisms capable of measuring andmodifying the position, angle, and/or separation distance of the torch16 relative to the part 12. Additionally, the robotic system 32 maycontrol operation of the torch 16 (e.g., activation/deactivation of thetorch 16, distance 48 that the metal-cored wire 14 electrode extendsfrom the torch 16). In certain embodiments, the part 12 beingmanufactured may, additionally or alternatively, be coupled to a roboticsystem, like the robotic system 32, capable of measuring and modifyingthe position, angle, and/or separation distance of the part 12 relativeto the torch 16.

Once the torch 16 illustrated in FIG. 1 is brought into proper positionby the robotic system 32, an arc 44 is struck between the part 12 andthe electrified aluminum metal-cored wire 14 that extends from the torch16. A portion of the aluminum metal-cored wire 14 is melted (e.g.,droplets 18) by the heat of the arc 44 and transferred to form a deposit20, and eventually a layer 22, of the part 12. In certain embodiments,the aluminum metal-cored wire 14 may be completely converted into moltendroplets 18 by the heat of the arc 44 before beings transferred to thepart 12 (e.g., electrospray transfer). In other embodiments, theelectrified aluminum metal-cored wire 14 may briefly contact the part12, and may form a brief short circuit that rapidly melts to form amolten droplet at the surface of the part 12 (e.g., controlledshort-circuit transfer).

As mentioned, the control system 24 of the illustrated additivemanufacturing system 10 has a controller 34, which includes a processor50 and a memory 52 that executes instructions to control the formationof the deposits 20 during the additive manufacturing of the part 12. Theillustrated controller system 24 includes an interface 54 (e.g., acomputer workstation) that is communicatively coupled to the controller34 and that provides parameters of the part 12 to the controller 34. Forexample, an operator may load a set of parameters for forming the part12 into the interface 54, such as a three-dimensional model (e.g.,computer aided design (CAD) model) produced by a three-dimensional 3DCAD tool. In some embodiments, the interface 54 and/or the controller 34may then produce a set of instructions in the memory 52 of thecontroller 34 that, when executed by the processor 50, cause theadditive manufacturing system 10 to produce the part 12 with a desiredcomposition and dimensions, based on the parameters received at theinterface 54.

In particular, the illustrated controller 34 is communicatively coupledto the various subsystems of the additive manufacturing system 10 (e.g.,the power system 26, the wire feed system 28, the gas supply system 30,and the robotic system 32) and capable of providing control signals toeach of these subsystems to cause the additive manufacture of the part12. Further, the illustrated controller 34 is capable of receivingoperational information from sensing devices 56 (e.g., positionalsensors, flow sensors, voltage sensors, current sensors, wire feed speedsensors, temperature sensors, thermal imaging devices, cameras, or othersuitable sensing devices) of these subsystems, and the processor 50 ofthe controller 34 may determine how to control these subsystems based onboth the operational information and the instructions for the part 12received from the interface 54. For example, the controller 34 maymonitor and control the outputs of the various subsystems, such as thecurrent/voltage output of the power system 26, the rate at which thealuminum metal-cored wire 14 is provided by the wire feeder system 28,the flow rate of the shielding gas provided by the gas supply system 30,and the positioning and movement of the torch 16, based on theinstructions for the part 12 and based on feedback provided by thesensing devices 56 of these subsystems.

Aluminum alloys are generally classified into wrought alloys and castalloys, and sub-classified into hardenable (e.g., heat-treatable) andnon-hardenable (e.g., non-heat-treatable) materials. The most commonalloying elements for aluminum alloys include: magnesium (Mg, meltingpoint (MP)=1202° F.), manganese (Mn, MP=2275° F.), copper (Cu, MP=1981°F.), silicon (Si, MP=2570° F.), iron (Fe, MP=2795° F.), titanium (Ti,MP=3034° F.), chromium (Cr, MP=3465° F.), nickel (Ni, MP=2647° F.), zinc(Zn, MP=788° F.), vanadium (V, MP=3434° F.), zirconium (Zr, MP=3366°F.), silver (Ag, MP=1764° F.), cadmium (Ni, MP=610° F.), lithium (Li,MP=358° F.), scandium (Sc, MP=2802° F.), lead (Pb, MP=622° F.), bismuth(Bi, MP=520° F.), tin (Sn, MP=450° F.), boron (B, MP=3767° F.), andberyllium (Be, MP=2349° F.). Pure aluminum has a melting point ofapproximately 1220° F., and low-alloy aluminum (e.g., 1xxx seriesaluminum alloy) can have a melting point that approaches 1215° F. Asdiscussed in detail below, various alloying elements in various rangescan increase or decrease the melting point (e.g., the solidus and/orliquidus) of an alloy in different ways.

With the foregoing in mind, FIGS. 2A and 2B illustrate schematic,cross-sectional views of different embodiments of a metal-cored aluminumwire 14. The metal-cored aluminum wire 14 illustrated in FIG. 2Aincludes a seamless, metallic sheath 62 that encircles (e.g., surrounds,contains) a compressed granular core 64. In contrast, the metal-coredaluminum wire 14 illustrated in FIG. 2B includes a metallic sheath 62that encircles (e.g., surrounds, contains) a compressed granular core64, and further includes a seam 66 (e.g., a flush seam or a folded/bentseam) where the edges of the metal strip used to manufacture the sheath62 meet. As discussed below, embodiments of the metal-cored aluminumwire 14 that lack a seam 66 may enable advantages in terms of reducedporosity within the additively manufactured part 12.

In certain embodiments, an additively manufactured aluminum part may bemanufactured by the method 100 illustrated in FIG. 3. According to thismethod 100, an additively manufactured aluminum part may be formed bythe steps of: (a) providing an aluminum alloy part at step 101; (b)establishing an arc between a metal-cored aluminum wire and the aluminumalloy part, wherein the metal-cored aluminum wire comprises a metallicsheath and a granular core disposed within the metallic sheath at step102; (c) melting a portion of the metal-cored aluminum wire using theheat of the arc to form molten droplets at step 103; (d) transferringthe molten droplets to the aluminum alloy part under an inert gas flowat step 104; (e) solidifying the molten droplets under the inert gasflow to form a plurality of deposits on the aluminum alloy part at step105; (f) fusing the plurality of deposits together to form a layer atstep 106; and (g) repeating steps 101 to 106 ((b) through (f) above) toform a plurality of layers at step 107, wherein the plurality of layersconstitutes an additively manufactured aluminum part at step 108.

In certain embodiments, the core 64 may account for less thanapproximately 20% (e.g., less than approximately 15%, less thanapproximately 10%, less than approximately 5%) of the weight of the wire14, and approximately 80% or more of the weight of the wire 14 may becontributed by the sheath 62. It may be appreciated that the overallcomposition of a metal-cored aluminum wire 14 may be generally tuned tomatch the desired composition of a particular part 12 beingmanufactured. Furthermore, the overall composition of the metal-coredaluminum wire 14 can be determined based on the composition of thesheath 62, the contribution of the sheath 62 to the total weight of thewire 14, the composition of the core 64, and the contribution of thecore 64 to the total weight of the wire 14.

As discussed above, a shielding gas may be provided by the shielding gassystem 32 to reduce oxygen and moisture content near the molten droplets18 and solidifying deposits 20 and layers 22. Since the shielding gasmay have a relatively high flow rate, it is presently recognized that aportion of the powdered core 64 of a metal-cored aluminum wire 14 can becarried away from the surface of the part 12 by the shielding gas. Forexample, when certain alloying elements are included in the core 64 aspure elemental powders (e.g., Mn, Ti, Si), the high melting point ofthese elemental powders can result in at least a portion the powdersbeing carried away by the shielding gas such that they do not melt tobecome incorporated into the part 12. This can undesirably reduce thedeposition rate of the additive manufacturing process, alter thecomposition of the deposit 20, the layer 22, and/or part 12, as well asincrease the amount of particulates in the additive manufacturingenvironment.

As such, for the disclosed metal-cored aluminum wire 14, at least onemetallic component within the core 64 of the wire 14 is an alloy havinga substantially lower melting point (or solidus) than the melting pointof the pure elements that make up the alloy. Additionally, in certainembodiments, at least one metallic component in the core 64 of the wire14 has a melting point (or solidus) that is substantially lower than themelting point (or solidus) of other powdered components of the core 64.For such embodiments, it is believed that these lower melting componentsof the core 64 are the first to melt as the temperature of the wire 14increases, and the higher melting powders are contained within (e.g.,surrounded, captured, or trapped by) the liquefied lower meltingcomponents and are not easily carried away by the shielding gas flow.Additionally or alternatively, in certain embodiments, the core 64 ofthe metal-cored aluminum wire 14 has a substantially lower melting point(or solidus) relative to the melting point (or solidus) of the sheath62. For such embodiments, the core 64 includes one or more powderedcomponents that begin to melt at a lower temperature than the sheath 62.For such embodiments, it is believed that the relatively higher meltingpoint (or solidus) of the sheath 62 enables the sheath 62 to remainintact to provide a path for current to flow until the core 64 ispartially or completely liquefied at or near the arc 44.

With the foregoing in mind, specific considerations for the sheath 62and the core 64 for embodiments of the metal-cored aluminum wire 14 areset forth below. For embodiments of the disclosed metal-cored aluminumwire 14, the metallic sheath 62 is formed from any suitable aluminumalloy. For example, in certain embodiments, the sheath 62 may be made oflow-alloy aluminum (e.g., Al 1100, pure aluminum), or other aluminumalloys (e.g., Al 6005, Al 6061). By specific example, in certainembodiments, the sheath 62 may be made from a 6xxx series aluminum alloy(e.g., Al 6063), which may have a melting point of approximately 1080°F. (solidus) to approximately 1210° F. (liquidus). In other embodiments,the sheath 62 may be made from a lower-alloy aluminum, such as a 1xxxseries aluminum alloy (e.g., Al 1100), which enables a higher meltingpoint (e.g., between a solidus of approximately 1190° F. and a liquidusof approximately 1215° F.) and easier extrusion.

As mentioned above with respect to FIG. 2A, in certain embodiments, thesheath 62 of the disclosed metal-cored aluminum wires 14 may lack a seamor similar discontinuity. In other embodiments, the metal-cored aluminumwires 14 may be fabricated by bending and compressing a metal strip toform the sheath 62 around the granular core material 64, resulting in aseam 66 (e.g., a flush seam or a folded/bent seam) along the sheath 62of the wire 14, as illustrated in FIG. 2B. Embodiments having a seamlesssheath 62, as illustrated in FIG. 2A, may be formed from a seamless,extruded tube of aluminum or aluminum alloy. By using a seamless sheath62, certain disclosed embodiments of the metal-cored aluminum wire 14are less likely to retain organic residue (e.g., lubricants) from theirfabrication process, and less likely to absorb moisture from theenvironment, than embodiments that include a seam 66. As such, thedisclosed embodiments of the seamless metal-cored aluminum wire 14, asillustrated in FIG. 2A, reduce the delivery of such hydrogen-containingmaterials to the molten deposit, thereby reducing the aforementionedissues of hydrogen-induced porosity in the resulting deposit.

As mentioned above, the granular core 64 of the disclosed metal-coredaluminum wire 14 is generally a compressed, homogenous mixture ofpowders, including one or more powdered metallic components. In certainembodiments, the core 64 may also include up to approximately 5% ofnon-metals components (e.g., fluxing components, slagging components,components to control surface tension, arc stability components,components to control viscosity of the molten droplet 18, exothermicelements or compounds capable of increasing the deposition temperature,etc.). For example, in certain embodiments, the core 64 may includeoxides (e.g., oxides of metals or metal alloys). By further example, incertain embodiments, the core 64 may include barium (Ba) to reduceporosity of the deposit. Additionally, as mentioned, it is generallydesirable for the core 64 to be substantially free of moisture, organiclubricants, or other sources of diffusible hydrogen.

The powdered metallic components of the core 64 of the disclosedmetal-cored aluminum wire 14 may be either pure metal powders, orpowders of alloys. For example, in certain embodiments, the powderedalloys of the core 64 may be binary alloys (i.e., made of two elements),ternary alloys (i.e., made of three elements), or quaternary alloys(i.e., made of four elements). For example, it may be appreciated that,in different embodiments, three alloying elements of the wire 14 (e.g.,Al, Mg, and Mn) may be included in the core 64 in different ways (e.g.,as a mixture of pure Al, pure Mg, and pure Mn; as a mixture of an Al—Mgalloy and pure Mn; as an Al—Mg—Mn alloy; as a mixture of an Al—Mg alloyand an Al—Mg—Mn alloy), which may be optimized for desiredcharacteristics of the part 12 and to minimize the amount of powderedcore 64 in the wire 14.

Additionally, as mentioned above, the one or more powdered metalliccomponents include at least one alloy having a substantially lowermelting point (or solidus) than the melting point of the individualelements of that alloy. For example, in certain embodiments, the alloymay be a eutectic or near-eutectic alloy. A eutectic alloy is an alloythat includes two or more elements having particular relativeconcentrations that define a eutectic composition. When only twoelements are present within a eutectic alloy, it is described as abinary eutectic system; however, systems with a greater number ofelements (e.g., ternary systems, quaternary systems, etc.) are alsopossible. A eutectic alloy has a sharp melting point (i.e., solidus andliquidus are substantially the same) at its eutectic temperature, whichis necessarily lower than each of the melting points of the individualelements that make up the alloy. It may be appreciated that not everyset of elements has a eutectic composition, for example,aluminum-titanium alloys and aluminum-manganese alloys do not have aeutectic composition. Furthermore, polyeutectic systems with multipleeutectic compositions for a given set of elements are possible as well.Regardless, for a set of elements that has at least one eutecticcomposition, the lowest eutectic temperature represents the lowestpossible melting point of the alloys that can be made from the set ofelements.

In certain embodiments, the core 64 of the metal-cored aluminum wire 14may include one or more binary eutectic alloys. More specifically, incertain embodiments, one or more of the binary eutectic alloys of thecore 64 may be aluminum binary eutectic alloys. A non-limiting list ofexample aluminum binary eutectics includes: aluminum-beryllium (0.8% Be;melting point (MP)=1191° F.), aluminum-copper (33% Cu; MP=1019° F.),aluminum-iron (98% Fe; MP=1211° F.), aluminum-lithium (93% Li; MP=351°F.), aluminum-magnesium (36% Mg, MP=844° F.; and an even lower meltingeutectic at 66% Mg; MP=819° F.), aluminum-silicon (12.6% Si; MP=1071°F.), and aluminum-zinc (94% zinc; MP=718° F.). In certain embodiments,ternary or quaternary eutectics of aluminum may be included in the core64. In certain embodiments, eutectics of non-aluminum alloys may beincluded in the core 64. A non-limiting list of example includestitanium-boron, titanium-zirconium and zirconium-vanadium. In certainembodiments, the core 64 may be composed entirely of one or moreeutectic alloys.

Additionally, in certain embodiments, the core 64 includes one or morepowdered components that begin to melt at a lower temperature than thesheath 62 as the temperature of the metal-cored wire 14 increases at ornear the arc 34. For example, in certain embodiments, the melting point(or solidus) of the sheath 62 may be at least 5% greater, at least 10%greater, at least 15% greater, at least 25% greater, at least 30%greater, at least 50% greater, or at least 70% greater than the meltingpoint (or solidus) of the core 64. By specific example, in anembodiment, a wire 14 may have a sheath 62 made from a low-alloyaluminum alloy with a solidus of approximately 1190° F. and a core 64that includes an aluminum-magnesium alloy with a melting point ofapproximately 819° F., such that the sheath 62 of the wire 14 has asolidus that is approximately 30% greater than the solidus of thegranular core 64.

In certain embodiments of the metal-cored aluminum wire 14, the core 64may include a mixture of metallic components, wherein at least onepowdered metallic component has a melting point (or solidus) that issubstantially lower than the melting points (or solidi) of otherpowdered metallic components of the core 64. For example, in certainembodiments, each metallic component of the core 64 may be classified aseither high-melting (e.g., melting point or solidi greater than 1000°F.) or low-melting (e.g., melting points or solidi less than 1000° F.)components. For such embodiments, it may be desirable to have asufficient amount of lower melting metallic components in the core 64such that, when these metallic components melt and liquefy, there is asufficient volume of these liquefied metallic components to contain(e.g., suspend, surround) the powders of the higher melting componentsof the core 64. For example, in certain embodiments, the lower meltingcomponents of the core 64 may account for greater than approximately15%, greater than approximately 25%, greater than approximately 40%, orgreater than approximately 60% of the core 64 by weight. It may be notedthat, in certain embodiments, one or more higher melting components ofthe core 64 may only partially melt or dissolve before becomingincorporated into the deposit of the additively manufactured part.

In certain embodiments, each metallic component of the core 64 (e.g.,aluminum-magnesium alloy, aluminum-silicon alloy) may be produced byhomogenously melting the elements of the metallic component in thedesired ratios to form a melt. The solidified melt may subsequently bemilled, and the resulting powder may be sieved and fractioned. It ispresently recognized that metallic powders produced in this manner havea lower oxygen content than powders produced by other methods (e.g.,water or gas atomized powders), and, therefore, produce less aluminaduring additive manufacturing. In certain embodiments, the milledpowders may have a grain size less than approximately 0.4 mm (e.g.,approximately 45 μm to approximately 250 μm) to facilitate tight packingwithin the core 64. It may be noted that, while increasing grain size ofthe particles may also reduce the amount of the granular core 64 thatcan be carried away by the shielding gas, too large of a grain size canresult in poor packing (e.g., excess void space) and undesired gastrapping within the core 64. After preparing each of the powderedcomponents of the core 64, the metallic components, as well as anynon-metallic components, may be combined and mixed to form asubstantially homogenous mixture of the powdered components of the core64.

As set forth above, in certain embodiments, the sheath 62 may be aseamless sheath that is formed from an extruded aluminum alloy. For suchembodiments, after cleaning an extruded aluminum tube to remove surfacecontaminates, the aforementioned homogenous mixture of the powderedcomponents of the core 64 may be added to the seamless sheath 62, forexample, using vibration filling. The filled sheath 62 also may,additionally or alternatively, be shaved to reduce the thickness of thesheath 62 and the diameter of the wire 14, as well as to provide a clean(e.g., oxide-free) surface to the wire 14. In certain embodiments, thewire 14 may, additionally or alternatively, be dried at a temperatureless than the solidus of the core 54, to ensure that the wire 50 issubstantially free of moisture. In certain embodiments, the wire 14 maybe soft annealed at a temperature less than the solidus of the core 64,which improves or increases the ductility of the wire 14. In certainembodiments, the wire 14 may be drawn to a final desired diameter and,subsequently, drawing lubricants and/or oxide layers may be removed fromthe surface of the seamless sheath 62.

It may also be noted that the disclosed aluminum metal-cored wire designenables the formulations of deposits to be modified for enhancedproperties. For example, the disclosed aluminum metal-cored wire 14enables the production of a binary deposit that includes Al and Si.However, the formulation of this example aluminum metal-cored wire 14may also be modified with the addition of a third alloying element, suchas Mg, in a suitable quantity to render the deposit 20, the layer 22, orthe part 12 as a whole, heat-treatable. As such, the aluminummetal-cored wire 14 enables flexibility that can enable enhancedproperties into a deposit with minor variations in the composition ofthe core 64 and/or wire 14.

Example 1

Table 1 describes a target composition for a deposit of a part (i.e., anAl 357 alloy deposit) capable of being formed using an embodiment of themetal-cored aluminum wire 14 during an additive manufacturing operation.It may be appreciated that elements indicated by maximum values aloneare not required to be present by the specification; however, theindicated maximum values should be respected in this example.

TABLE 1 Desired deposit composition and melting points for each of thealloying elements for example 1. Element wt % Melting Point (° F.) Si6.5-7.5 2570 Fe 0.15 max 2795 Cu 0.05 max 1981 Mn 0.03 max 2275 Mg0.45-0.6  1202 Zn 0.05 max 788 Ti 0.20 max 3038 Others (each) 0.05 maxOthers (total) 0.15 max Al remainder 1220

Table 2 includes the composition of the sheath 62, the core 64, and thetotal wire 14 for an embodiment of the metal-cored aluminum wire 14capable of providing the deposit chemistry set forth above with respectto Table 1. For the example wire 14 represented in Table 2, the sheath62 is an Al 6063 seamed or seamless sheath having the indicatedcomposition. The core 64 of the example wire 14 is a mixture of threedifferent powders, two of which (i.e., Al—Si and Al—Mg) are alloyshaving substantially lower melting points than the melting points of theindividual elements of the respective alloys (i.e., Al, Si, and Mg).Additionally, for the example wire 14, the Al—Mg alloy is a eutecticalloy having the lowest possible melting point of all Al—Mg alloys.Also, for the example wire 14, the Al—Si alloy has a substantially lowermelting point than the pure Ti powder of the core 64 and is present insuitable quantities to liquefy and surround (e.g., trap, capture) thepowdered Ti component of the core 64, as discussed above. Furthermore,the melting point of the sheath 62, namely 1140° F. (solidus)-1210° F.(liquidus), is substantially greater than the solidus of the core 64,namely 819° F.

TABLE 2 Breakdown of the composition and contribution of the sheath 62and the core 64 of the example embodiment of the metal-cored aluminumwire 14 for example 1, with the remaining elemental composition of thewire being aluminum and trace elements. Sheath (Al 6063) Core TotalPortion of Elemental Melting Elemental Elemental Wire that ContributionPoint of wt % wt % Contribution Composition wt % in is Sheath to WireAlloy in Alloy Element Alloy to Wire of Wire Sheath (wt %) (wt %) Core(° F.) in Alloy in Wire (wt %) (wt %) Si 0.55 86.0 0.47 Al—Si 1868 5013.80 6.9 7.37 Mg 0.6 0.52 Al—Mg 819 66 0.10 0.066 0.58 Ti 0.05 0.04 Ti3038 100 0.10 0.1 0.14

Example 2

Table 3 describes another target composition of a deposit capable ofbeing formed using another embodiment of the metal-cored aluminum wire14 in an additive manufacturing operation. It may be appreciated thatelements indicated by maximum values alone are not required to bepresent by the specification; however, the indicated maximum valuesshould be respected in this example. Compared to the target deposit ofTable 1, the target deposit composition set forth in Table 3 indicates ahigher content of particular alloying elements, particularly Mg and Mn.

TABLE 3 Desired deposit composition and melting points for each of thealloying elements for example 2. Element wt % Melting Point (° F.) Si0.6 max 2570 Fe 0.4 max 2795 Cu 0.1 max 1981 Mn 0.9-1.5 2275 Mg 5.6-6.61202 Cr 0.05-0.20 3385 Ti 0.05-0.20 3038 Al remainder 1220

It may be appreciated that the higher Mg and Mn content indicated inTable 3 may be useful to particular applications where enhanced partstrength is desired. It may be useful to have the ability to raise Mnconcentrations to maintain strength while lowering Mg content to improvethe corrosion resistance of the part 12 in corrosive environments (e.g.,marine environments), without being limited by solid wire manufacturingconstraints associated with high Mn concentrations. The higher amountsof alloying elements set forth in Table 3 are more common among wroughtaluminum alloys; however, it may be noted that even greater amounts ofthese alloying elements may be present in casting aluminum alloys. Itshould be noted that producing a solid-core aluminum wire capable ofproducing a deposit having the amounts of Mg and Mn indicated in Table3, let alone even greater amounts, is impractical since drawing thesolid wire becomes substantially more difficult with increasing contentof these alloying elements. As such, embodiments of the disclosedmetal-cored aluminum wire 14 enable the formation of high-alloy aluminumdeposits, like the deposit indicated in Table 3, that are not possibleor practical without the use of the metal-cored aluminum wire 14described herein.

Table 4 includes the composition of the sheath 62, the core 64, and thetotal wire 14 for an embodiment of the metal-cored aluminum wire 14capable of providing the deposit chemistry set forth above with respectto Table 3. For the example wire 14 represented in Table 4, the sheath62 is an Al 6063 seamed or seamless sheath having the indicatedcomposition. The core 64 of the example wire 14 is a mixture of fourdifferent powders, two of which (i.e., Al—Mg and Al—Mn) are alloyshaving substantially lower melting points than the melting points of theindividual elements of the respective alloys (i.e., Al, Mg, and Mn).Additionally, for the example wire 14, the Al—Mg alloy is a eutecticalloy having the lowest possible melting point of all Al—Mg alloys.Also, for the example wire 14, the Al—Mg alloy has a substantially lowermelting point than the other powdered components of the core 64, and itpresent in suitable quantities to liquefy and surround (e.g., trap,capture) the higher-melting powdered components of the core 64, asdiscussed above. Furthermore, the melting point of the sheath 62, namely1140° F. (solidus)-1210° F. (liquidus), is substantially greater thanthe solidus of the core 64, namely 819° F.

TABLE 4 Breakdown of the composition and contribution of the sheath 62and the core 64 of the example embodiment of the metal-cored aluminumwire 14 for example 2, with the remaining elemental composition of thewire being aluminum and trace elements. Sheath (Al 6063) Core TotalPortion of Elemental Melting Elemental Elemental Wire that ContributionPoint of wt % wt % Contribution Composition wt % in is Sheath to WireAlloy in Alloy Element Alloy to Wire of Wire Sheath (wt %) (wt %) Core(° F.) in Alloy in Wire (wt %) (wt %) Si 0.55 85.8 0.47 — — — — — 0.47Mg 0.6 0.51 Al—Mg 819 66 9.00 5.94 6.45 Ti 0.05 0.04 Ti 3038 100 0.100.1 0.14 Cr 0.08 0.07 Cr 3385 100 0.10 0.1 0.17 Mn — — Al—Mn 1652 255.00 1.25 1.25

Example 3

Table 5 describes another target composition (similar to Al 7005, usedfor weldable aluminum extrusions) of a deposit capable of being formedusing an embodiment of the metal-cored aluminum wire 14 in an additivemanufacturing operation. It may be appreciated that elements indicatedby maximum values alone are not required to be present by thespecification; however, the indicated maximum values should be respectedin this specific example.

TABLE 5 Desired deposit composition and melting points for each of thealloying elements for example 3. Element wt % Melting Point (° F.) Si0.35 max  2570 Fe 0.4 max 2795 Cu 0.1 max 1981 Mn 0.2-0.7 2275 Mg1.0-1.8 1202 Cr 0.06-0.02 3385 Zn 4.0-5.0 788 Ti 0.01-0.06 3038 Zr0.08-0.20 3366 Al remainder 1220

It may be appreciated that the higher alloying element content indicatedin Table 5 may be useful to particular applications, for example, toprovide a heat-treatable aluminum alloy having a composition similar tothe Al 7005 alloy. This may be more useful than other aluminum alloys(e.g., 5356 aluminum alloy), which may be easier to produce due to theirlower alloy content, but do not provide a heat-treatable deposit orpart. In contrast, embodiments of the disclosed metal-cored aluminumwire 14 enable the formation of high-alloy, heat-treatable aluminumdeposits, like the deposit indicated in Table 5, which may not bepossible or practical without the use of the metal-cored aluminum wire14 described herein.

Table 6 includes the composition of the sheath 62, the core 64, and thetotal wire 14 for an embodiment of the metal-cored aluminum wire 14capable of providing the deposit chemistry set forth above with respectto Table 5. For the example wire 14 represented in Table 6, the sheath62 is an Al 1100 seamed or seamless sheath having the indicatedcomposition. The core 64 of the example wire 14 is a mixture of sixdifferent powders, four of which (i.e., Al—Mn, Al—Mg, Al—Zn, and Ti—Zr)are alloys having substantially lower melting points than the meltingpoints of the individual elements of the respective alloys (i.e., Al,Mn, Mg, Zn, Ti, and Zr). Additionally, for the example wire 14, theAl—Mg and Al—Zn alloys are eutectic alloys having the lowest possiblemelting points of all Al—Mg and Al—Zn alloys, respectively. Also, forthe example wire 14, both the Al—Mg and Al—Zn alloys have substantiallylower melting points than the other powdered components of the core 64,and are present in suitable quantities to melt before and surround(e.g., trap, capture) the higher-melting powdered components of the core64, as discussed above. Furthermore, the melting point of the sheath 62,namely 1190° F. (solidus)-1215° F. (liquidus), is substantially greaterthan the solidus of the core 64, namely 718° F.

TABLE 6 Breakdown of the composition and contribution of the sheath 62and the core 64 of the example embodiment of the metal-cored aluminumwire 14 for example 3, with the remaining elemental composition of thewire being aluminum and trace elements. Sheath (Al 1100) Core TotalPortion of Elemental Melting Elemental Elemental Wire that ContributionPoint of wt % wt % Contribution Composition wt % in is Sheath to WireAlloy in Alloy Element Alloy to Wire of Wire Sheath (wt %) (wt %) Core(° F.) in Alloy in Wire (wt %) (wt %) Si 0.3 87.86 0.26 — — — — — 0.26Fe 0.3 0.26 — — — — — 0.26 Cu 0.04 0.04 — — — — — 0.04 Mn — — Al—Mn 165225 1.00 0.25 0.25 Mg — — Al—Mg 819 66 2.00 1.32 1.32 Ti — — Ti 3038 1000.01 0.01 0.06 Ti—Zr ~1800 34.4 0.15 0.05 Cr — — Cr 3385 100 0.10 0.100.10 Zn — — Al—Zn 718 94 5.00 4.70 4.70 Zr — — Ti—Zr ~1800 65.6 0.150.10 0.10

Example 4

Table 7 describes another target composition of a deposit (based on Al520.0, an aluminum casting alloy) capable of being formed using anembodiment of the metal-cored aluminum wire 14 in an additivemanufacturing operation. It may be appreciated that elements indicatedby maximum values alone are not required to be present by thespecification; however, the indicated maximum values should be respectedin this example.

TABLE 7 Desired deposit composition and melting points for each of thealloying elements for example 4. Element wt % Melting Point (° F.) Si0.25 max 2570 Fe  0.3 max 2795 Cu 0.25 max 1981 Mn 0.15 max 2275 Mg9.5-10.6 1202 Zn 0.15 max 788 Ti 0.25 max 3038 Al remainder 1220

It may be appreciated that the higher Mg content indicated in Table 7may be useful to particular applications, for example, to provide aheat-treatable aluminum alloy having a composition similar to the Al520.0 alloy. Embodiments of the disclosed metal-cored aluminum wire 14enable the formation of high-alloy, heat-treatable, aluminum deposits,like the deposit indicated in Table 7, which are not possible orpractical without the use of the metal-cored aluminum wire 14 describedherein.

Table 8 includes the composition of the sheath 62, the core 64, and thetotal wire 14 for an embodiment of the metal-cored aluminum wire 14capable of providing the deposit chemistry set forth above with respectto Table 7. For the example wire 14 represented in Table 8, the sheath62 is an Al 1100 seamed or seamless sheath having the indicatedcomposition. The core 64 of the example wire 14 is a single powderedalloy, Al—Mg, which is an alloy having a substantially lower meltingpoint than the melting points of the individual elements of the alloys(i.e., Al and Mg). Additionally, for the example wire 14, the Al—Mg is aeutectic alloy having the lowest possible melting point of all Al—Mgalloys. Furthermore, the melting point of the sheath 62, namely 1190° F.(solidus)-1215° F. (liquidus), is substantially greater than the solidusof the core 64, namely 819° F.

TABLE 8 Breakdown of the composition and contribution of the sheath 62and the core 64 of the example embodiment of the metal-cored aluminumwire 14 for example 4, with the remaining elemental composition of thewire being aluminum and trace elements. Sheath (Al 1100) Core TotalPortion of Elemental Melting Elemental Elemental Wire that ContributionPoint of wt % wt % Contribution Composition wt % in is Sheath to WireAlloy in Alloy Element Alloy to Wire of Wire Sheath (wt %) (wt %) Core(° F.) in Alloy in Wire (wt %) (wt %) Si 0.3 84.5 0.26 — — — — — 0.26 Fe0.3 0.26 — — — — — 0.26 Cu 0.04 0.04 — — — — — 0.04 Mg — — Al—Mg 819 6615.50 10.23 10.23

Example 5

Table 9 describes another target composition of a deposit (based on Al206.0, an aluminum structural casting alloy) capable of being formedusing an embodiment of the metal-cored aluminum wire 14 in an additivemanufacturing operation. It may be appreciated that elements indicatedby maximum values alone are not required to be present by thespecification; however, the indicated maximum values should be respectedin this example.

TABLE 9 Desired deposit composition and melting points for each of thealloying elements for example 5. Element wt % Melting Point (° F.) Si0.1 max 2570 Fe 0.15 max  2795 Cu 4.2-5.0 1981 Mn 0.2-0.5 2275 Mg0.15-0.35 1202 Ti 0.15-0.3  3038 Zn 0.1 max 788 Al remainder 1220

Aluminum alloy 206.0 is commonly used for structural castings inheat-treated temper for automotive, aerospace, and other applicationswhere high tensile strength, high yield strength, moderate elongation,and high fracture toughness are desired. Examples of parts that can bemade using alloy 206.0 include gear housings and truck spring hangercastings. Embodiments of the disclosed metal-cored aluminum wire 14enable the formation of high-alloy, heat-treatable, aluminum deposits,like the deposit indicated in Table 9, which are not possible orpractical without the use of the metal-cored aluminum wire 14 describedherein.

Table 10 includes the composition of the sheath 62, the core 64, and thetotal wire 14 for an embodiment of the metal-cored aluminum wire 14capable of providing the deposit chemistry set forth above with respectto Table 9. For the example wire 14 represented in Table 10, the sheath62 is an Al 1100 seamed or seamless sheath having the indicatedcomposition. The core 64 of the example wire 14 is a mixture of fourdifferent powders, three of which (i.e., Al—Cu, Al—Mn, and Al—Mg) arealloys having substantially lower melting points than the melting pointsof the individual elements of the respective alloys (i.e., Al, Cu, Mn,and Mg). Additionally, for the example wire 14, the Al—Cu and Al—Mgalloys are eutectic alloys having the lowest possible melting points ofall Al—Cu and Al—Mg alloys, respectively. Also, for the example wire 14,both the Al—Cu and Al—Mg alloys have substantially lower melting pointsthan the other powdered components of the core 64, and are present insuitable quantities to melt before and surround (e.g., trap, capture)the higher-melting powdered components of the core 64, as discussedabove. Furthermore, the melting point of the sheath 62, namely 1190° F.(solidus)-1215° F. (liquidus), is substantially greater than the solidusof the core 64, namely 819° F.

TABLE 10 Breakdown of the composition and contribution of the sheath 62and the core 64 of the example embodiment of the metal-cored aluminumwire 14 for example 5, with the remaining elemental composition of thewire being aluminum and trace elements. Sheath (Al 1100) Core TotalPortion of Elemental Melting Elemental Elemental Wire that ContributionPoint of wt % wt % Contribution Composition wt % in is Sheath to WireAlloy in Alloy Element Alloy to Wire of Wire Sheath (wt %) (wt %) Core(° F.) in Alloy in Wire (wt %) (wt %) Si 0.03 84.25 0.03 — — — — — 0.03Fe 0.12 0.10 — — — — — 0.12 Cu 0.09 0.08 Al—Cu 1018 33 13.80 4.55 4.63Mn — — Al—Mn 1652 25 1.30 0.33 0.33 Mg — — Al—Mg 819 66 0.40 0.26 0.26Ti 0.005 0.00 Ti 3038 100 0.25 0.25 0.26

While only certain features of the present disclosure have beenillustrated and described herein, many modifications and changes willoccur to those skilled in the art. It is, therefore, to be understoodthat the appended claims are intended to cover all such modificationsand changes as fall within the true spirit of the present disclosure.

The invention claimed is:
 1. A method of forming an additivelymanufactured aluminum part, comprising: (a) providing an aluminum alloypart; (b) establishing an arc between a metal-cored aluminum wire andthe aluminum alloy part, wherein the metal-cored aluminum wire comprisesa metallic sheath and a granular core disposed within the metallicsheath; (c) melting a portion of the metal-cored aluminum wire using theheat of the arc to form molten droplets; (d) transferring the moltendroplets to the aluminum alloy part under an inert gas flow; (e)solidifying the molten droplets under the inert gas flow to form aplurality of deposits on the aluminum alloy part; (f) fusing theplurality of deposits together to form a layer; and (g) repeating steps(b) to (f) above to form a plurality of layers, wherein the plurality oflayers constitutes an additively manufactured aluminum part.
 2. Themethod of claim 1, comprising providing, via a controller of an additivemanufacturing system, a control signal to a robotic system of theadditive manufacturing system to position a torch of the additivemanufacturing system relative to the aluminum alloy part, wherein thetorch receives and supplies the metal-cored aluminum wire and the inertgas flow toward the aluminum alloy part.
 3. The method of claim 2,comprising providing, via the controller, a control signal to activate awire feed system of the additive manufacturing system to feed themetal-cored aluminum wire to the torch of the additive manufacturingsystem at a particular wire feed speed.
 4. The method of claim 3,comprising providing, via the controller, a control signal to activate agas supply system of the additive manufacturing system to provide theinert gas flow to the torch of the additive manufacturing system at aparticular inert gas flow rate.
 5. The method of claim 4, comprisingproviding, via the controller, a control signal to activate a powersystem of the additive manufacturing system to provide power toestablish the arc between the metal-cored aluminum wire and the aluminumalloy part at a particular voltage and a particular current.
 6. Themethod of claim 1, wherein the metallic sheath is a 6xxx series aluminumalloy or a 1 xxx series aluminum alloy.
 7. The method of claim 1,wherein the metallic sheath of the metal-cored aluminum wire is aseamless metallic sheath comprising an extruded aluminum alloy tube. 8.The method of claim 1, wherein the solidus of the metallic sheath of themetal-cored aluminum wire is at least 5% greater than the solidus of thefirst alloy.
 9. The method of claim 1, wherein the granular core of themetal-cored aluminum wire includes a first alloy comprising a pluralityof elements, and wherein the first alloy has a solidus that is lowerthan each of the respective melting points of the plurality of elementsof the first alloy.
 10. The method of claim 9, wherein the first alloyis a eutectic alloy or near-eutectic alloy.
 11. The method of claim 9,wherein the granular core of the metal-cored aluminum wire includes asecond alloy that is a eutectic or near-eutectic alloy.
 12. The methodof claim 9, wherein the granular core of the metal-cored aluminum wireincludes additional alloys, wherein each of the additional alloys has asolidus that is higher than the solidus of the first alloy, and whereinthe granular core comprises greater than 25% of the first alloy byweight.
 13. The method of claim 1, wherein the additively manufacturedaluminum part consists essentially of the deposits.
 14. The method ofclaim 1, wherein the inert gas flow comprises argon, helium, or amixture of argon and helium.
 15. The method of claim 14, wherein theinert gas flow comprises 100% argon or 100% helium.
 16. The method ofclaim 14, wherein the inert gas flow comprises 50% argon and 50% helium,or 25% argon and 75% helium.
 17. The method of claim 1, wherein thegranular core of the metal-cored aluminum wire comprises aluminum,magnesium, and manganese.
 18. The method of claim 1, wherein thegranular core of the metal-cored aluminum wire comprises analuminum-silicon alloy, an aluminum-magnesium alloy, and titanium. 19.The method of claim 1, wherein the granular core of the metal-coredaluminum wire comprises an aluminum-manganese alloy, analuminum-magnesium alloy, titanium, and chromium.
 20. The method ofclaim 1, wherein the granular core of the metal-cored aluminum wirecomprises an aluminum-manganese alloy, an aluminum-magnesium alloy,titanium, a titanium-zirconium alloy, chromium, an aluminum-zinc alloy,and a titanium-zirconium alloy.